Archive: This article was first published in 2023. It reflects the state of knowledge, product names and wording of that time. Current, product-specific information can be found on the respective product pages.
Long-Term Hygiene as the Hallmark of the “City on the River”
To protect its new sandstone benches on the Neckarlauer against dirt, bird droppings, chewing gum, graffiti and the growth of algae and moss, the City of Heidelberg had the stone surfaces refined with the high-performance coating from Nanopool. The invisible multifunctional layer against dirt adhesion and weathering residues is designed to allow natural contamination on the surfaces to be washed away largely by rain. This makes the recreational area on the riverbank even more attractive.
Moisture and moss cushions can form a wafer-thin biofilm on stone surfaces that permanently damages the substrate and delays the drying of the stones. The professional NP® coating is designed to counteract this and thus enhances material protection and comfort in equal measure. The treated surface is altered neither visually nor to the touch.
High Quality: Natural Stone Remains Breathable
In contrast to many common, conventional stone impregnations, the NP® coating gives natural stone its new, repellent properties without sealing it airtight: the layer is so ultra-thin that it wraps around the individual grains and therefore does not close pores and joints.
As a result, the stone dries quickly and without restriction when moisture enters from the underside. This was also confirmed in an official expert report by the Institut für Steinkonservierung e. V.: In cooperation with Dr. Tombers & Partner – Gesellschaft für Bauschadensforschung, Materialprüfung und Umweltanalytik mbH, the water vapour diffusion resistance value µ was determined for the Nanopool product. The results showed that despite the high protective effect of the multi-performance layer, the water vapour permeability of the treated sandstone sample corresponds to that of an untreated stone.
Protection Against Driving Rain and Freeze-Thaw
Natural stone in particular can be severely damaged by weathering over time. Among other things, capillary action during driving rain leads to moisture penetration of the stone, which not only causes mould and algae infestation but also gradually triggers a bursting of the substrate during freeze-thaw cycles.
The NP® protective coating is designed to counteract this: it can considerably reduce the penetration of moisture into the stone and thus a key cause of changes to the material – depending on the substrate, application and conditions of use.
The Institut für Steinkonservierung e.V. found, among other things:
- Tests on different stone samples show that the water-repellent effect of NP® Stone Protect is long-lasting in the tested samples, while at the same time the drying of the stone is not impaired when moisture enters from the rear side.
- On a sample exposed outdoors for several years, no changes to the stone surface have been observed so far. Untreated stone samples and those treated with conventional hydrophobing agents partly show microbial growth, whereas the samples treated with the (NP®) spray do not.
- The freeze-thaw cycle test and the freeze-de-icing-salt cycle test demonstrated that the NP® product remains effective even after 100 test cycles.
- The adhesion of moss and the formation of algae can be reduced without biocidal additives – depending on the substrate, application and conditions of use.